A printed circuit board is prepared by, e.g., either coating a copper surface of a copper-clad laminate or a surface of a flexible printed board with a solution of a photopolymerizable resin composition, or laminating on the surface of a copper substrate a photopolymerizable film formed by previously coating or pouring the composition into a film to form a resist film, selectively exposing the resist film to an actinic radiation to form a latent image, developing said image with a developer comprising an aqueous alkaline solution or the like to form a resist image on the copper substrate, and subjecting the copper surface not protected by the resist image to etching treatment or metal plating.
Particularly, in recent years, a laminate having a three-layer structure which is developable with an aqueous alkaline solution and flexible, i.e., a dry film resist comprising a support film layer, a photopolymerizable resin layer, and a protective film, has been strongly demanded in order to improve workability, the problem of air pollution, and yield.
In general, a resin composition comprising a carboxylated acrylic copolymer, a photopolymerizable monomer, and a photopolymerization initiator has been employed as the photopolymerizable resin composition developable with an aqueous alkaline solution.